neuro stuff.

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Okay, so I've been watching Firefly a lot recently. Yesterday I was watching the one where Simon sneaks River into the medical facility to get a 3D map of her brain. He talks about how her amygdala has been stripped, and that is why she feels everything all at once. He says something like "when you have a traumatic experience, and you try to forget it, your amygdala is what allows you to push it to the back of your mind.
I was just wondering how accurate this is?

First off I think this needs to be moved to the Television, Film, and Video sub-forum, also Firefly is awesome as was Serenity. As for your question, the amygdala is related to memory and emotional reactions as well as being linked to PTSD so that would make sense but I am not sure how accurate it is.

I wasn't sure whether to put it there or not, because it wasn't really about Firefly..super sorry! xx

I don't know what "stripped" in this context means. If it means taken out or damaged significantly, usually one of the things that happens is that her fear response would be screwed up. If you think living without fear would be a good thing, imagine what would happen if you encountered a poisonous snake or a mugger without any fear for your safety. People and animals with damaged amygdalas typically are less emotional, not more, and have trouble learning connections between emotionally charged stimuli and behaviors.

There is a syndrome known as Kluver-Bucy syndrome which is a form of amygdala damage. Common symptoms in people include losing fear and aggression, sticking weird things in your mouth and eating changes, and losing the ability to recognize familiar objects and people.

This article is about the life of a woman known as SM who has an amygdala damaged on both sides: http://abcnews.go.com/Health/MindMoodNews/woman-iowa-damaged-amygdala-shows-fear/story?id=12404875

Interestingly, they've done experiments and she can still have panic attacks, indicating the panic response is different than regular fear. One hypothesis is that the amygdala helps regulate fear in general, and can help calm you down, so without the amygdala her panic under the experimental conditions is actually worse: http://bps-research-digest.blogspot.com/2013/02/extreme-fear-experienced-without.html

As to the second part, your amygdala does help regulate fear and memory, but suppressing fearful memories involves your prefrontal cortex (the part of your brain responsible for complicated thinking and decision making) directing your amygdala, visual areas, and hippocampus (the memory part of your brain) to shut up.
http://www.newscientist.com/article/dn12254-scans-reveal-how-we-suppress-traumatic-memories.html

Okay, thank you so much Grand Autismo; I'm actually understanding what you said there! In Firefly, her amygdala had been completely removed I believe, but she was almost the exact opposite of what you're saying would happen. She lived in constant fear rather than no fear at all. Would this be caused by damage to another area of the brain?

The amygdala regulates fear, but why people develop anxiety disorders or 'live in constant fear' as the TV character does, isn't well understood yet. What some scientists think at the moment (it must still be researched more) is that there is a mistake in a particular gene. This gene has the information for a receptor (a kind of gate) that lets an opium like substance into the nerve cell. Normally, if we're frightened, the fear will go away after a while. It's (probably) this opium like substance that makes the fear go away. But if the 'gate' for that substance doesn't work anymore, the fear doesn't go away.

But there is still a lot we don't know about how the brain works, so you shouldn't take this as 'fact'. It's a possible explanation. Perhaps there are also other explanations scientists don't know about yet.

I would think the real life equivalent of living in constant fear would be something like having a severe anxiety disorder, as NewDawn said. It seems easier to induce lack of fear by damaging parts of the brain than inducing constant anxiety or fear. Severe anxiety involves things going wrong at multiple parts of the brain at multiple levels (i.e. from the neuron level all the way up to functional "pieces" of the brain).

From the brief research I did, I found out that in rats, lesions of various areas in the medial prefrontal cortex cause exaggerated fear responses to various stimuli. I don't think that would cause constant fear though, just more fear when encountering something scary.

Generally it is overactivation of a whole host of areas (such as various areas of the limbic system, which includes our friend the amygdala, and that other guy, the hippocampus) that causes anxiety, rather than underactivation (removal would be an extreme case of underactivation since it is not there any more to be activated).

As NewDawn said, the neuroscience of anxiety isn't well understood. The explanation she gave you is at the level of neurons and neurotransmitters. Anxiety, fear, and panic (which are oddly enough different reactions) are complicated things, and when they go wrong, they go wrong in a lot of different places.

If you wanted to induce constant fear in somebody, the closest things I could find that you could do to them medically would be to

1. Directly stimulate the amygdala with electricity (this can happen naturally as a part of temporal lobe seizures, it's known as "ictal fear" when part of a seizure)
2. Induce a panic response repeatedly with sodium lactate infusions or by inhaling air with extra carbon dioxide in it (although only some people are reliably panicked by these, mostly people with preexisting panic problems)

the amygdala thing is a good sci fi McGuffin. I seriously doubt his has any real scientific validity.

It is. The amygdala is what makes short terms memories into long term memories and it also regulates a lot of emotions.

There was an article just this week about a scientist that is about to start human trials on a device that mirrors the long term memory creation functions of the amygdala and can 'make' the brain store information in long term memory with the push of a button. Works in mice and animal tests..soon coming to humans.

Can you imagine how wonderful it would be to use this in a classroom setting? You'd get your PhD by age 16. Its eidetic memory by pushing a button.

I only have 1 amygdala (left). My right was removed a few years ago because of a (non-cancerous) tumor in it that I was born with.

Not the same as River or the studies already quoted, however from my own experience I would say:
I had difficulty regulating fear (terrible anxiety most of my life) with the tumor in my right amygdala. I got it under control with therapy tools about 10 years ago.

The removal of the amygdala did not increase my anxiety, if anything it may have reduced my fear response but it's hard to say because I had already achieved a pretty good hold on things by then.

I have always, and still do, have trouble processing emotions in real time, in myself and others. Anytime I get a lot of input or excitement or activity I need a lot of downtime to decompress or I overload and meltdown. This may be similar to what they meant in that episode (too bad if so, I've always felt like more of a Kaylee than a River - geek girls unite!)

It has definitely had an impact on how I learn and make new memories. I've always been 'hands on' but since the surgery it's been way worse than before - I pretty much can't do declarative or book learning.